I am new to this forum even though I have been reading it for some time. I reciently had my custom 300 wby built on a sako long action stolen while on a hunting trip to Quebec. I am considering replacing it with either a weatherby 338-378 accurmark or building one out of a 700 ss sendaro action in the 338-300 RUM. I have considered price of brass and so forth but nowhere have I been able to find any loading data for the 338-300 to see how close it comes to the 338-378 wby. Can anyone supply me with some loads for this caliber which can help me make my decision? Also I would like to know if these cases can be formed from both the 300 RUM and 375 RUM. Using the 300 RUM will result on a thinner case neck where as if 375 RUM brass were necked down to 338 this would result in a thicker walled neck. Any information will be appreciated.